INTRODUCTION The radiation sterilization industry traces its origin back to over 50 years ago. The first irradiator for commercial sterilization of medical device products came on-line in the United States in the 1950s. Over the intervening 50 years, radiation in the form of high-energy electrons produced by high-power accelerators or gamma rays produced by radioisotopes has been used to terminally sterilize a broad spectrum of medical devices and different types of pharmaceutical products. More recently a third source of radiation; that is, X-ray (bremsstrahlung) radiation has been introduced to the radiation sterilization industry. The proven efficacy of the process and available methodologies to validate a sterility assurance level (SAL) of 106 has made radiation an attractive alternative for terminal sterilization of many types of products. Because radiation sterilization is classified as a cold process, it also can be used to sterilize heat-labile products. As a final attribute, products that have been radiation sterilized can be released on the basis of certification of the absorbed dose of radiation delivered to the product, that is, dosimetric release. There is no need to conduct postirradiation sterility testing of the product, thereby expediting time to market for critical products and cost for the sterility tests.